FRET is a framework for the elicitation, specification, formalization, and analysis of system requirements. It enables users to specify unambiguous requirements using restricted English sentences while providing multiple representations to enhance clarity and validation of semantics. These representations include natural language descriptions, formal mathematical logics, and visual diagrams, allowing users with different expertise to review and understand the precise meaning of each requirement.
FRET supports hierarchical requirement definition, enabling users to organize requirements based on different levels. It also offers export capabilities in various formats, facilitating integration with external formal analysis tools. FRET provides automated, requirement-based test case generation, incorporating a coverage metric to assess the adequacy of generated tests. Furthermore, FRET includes built-in consistency checking mechanisms to detect conflicts between requirements and thus, it helps to ensure that requirements are complete and correct.
For more details, refer to the FRET manual.
For further information on FRET, please contact [email protected] and [email protected].
You can also report issues and participate in discussions on GitHub.
See installation guide.
See troubleshooting.
See release notes.
FRET has been tested across a variety of architecture and operating system combinations. It has been validated on multiple versions and distributions of macOS, Linux and Windows.
See contributors list.
We accept external contributions under a Contributor License Agreement (CLA):
For a comprehensive collection of FRET-related research, development and case studies, please refer to the publications section. This includes scholarly works that highlight the features and applications of FRET.
Copyright © 2025, United States Government as represented by the Administrator of the National Aeronautics and Space Administration. All rights reserved.
The FRET : Formal Requirements Elicitation Tool - Version 3.0 software is licensed under the Apache License, Version 2.0; you may not use this application except in compliance with the License. You may obtain a copy of the License here.
Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
